J Cell Sci. 2012 May 28. [Epub ahead of print]
Toxofilin upregulates the host cortical actin cytoskeleton dynamics facilitating Toxoplasma invasion
Delorme-Walker V, Abrivard M, Lagal V, Anderson K, Perazzi A, Gonzalez V, Page C, Chauvet J, Ochoa W, Volkmann N, Hanein D, Tardieux I.
Toxoplasma, a human pathogen and a model apicomplexan parasite, actively and rapidly invades host cells. To initiate invasion, the parasite induces the formation of a parasite-cell junction, progressively propels itself through the junction inside a newly formed vacuole that encloses the entering parasite. Litle is known how a few micron-large diameter parasite overcome the host cell cortical actin barrier to support these remarkably rapid process of internalization (< few seconds). Correlative light and electron microscopy in conjunction with electron tomography and three-dimensional image analysis indicate that toxofilin an actin-binding protein, secreted by invading parasites correlates with localized sites of disassembly of the host cell actin meshwork. Moreover, quantitative fluorescence speckle microscopy in cells expressing toxofilin indicates that toxofilin regulates actin filament disassembly and turnover. Furthermore, Toxoplasma tachyzoites lacking toxofilin, are impaired in cortical actin disassembly and exhibit delayed invasion kinetics. We propose that toxofilin locally upregulates actin turnover thus increasing depolymerization events at the site of entry that, in turn loosens the local host cell actin meshwork, facilitating parasite internalization and vacuole folding.
PMID: 22641695 [PubMed - as supplied by publisher]
Wednesday, May 30, 2012
Neuronal gp130 Expression Is Crucial to Prevent Neuronal Loss, Hyperinflammation, and Lethal Course of Murine Toxoplasma Encephalitis
Am J Pathol. 2012 May 25. [Epub ahead of print]
Neuronal gp130 Expression Is Crucial to Prevent Neuronal Loss, Hyperinflammation, and Lethal Course of Murine Toxoplasma Encephalitis
Händel U, Brunn A, Drögemüller K, Müller W, Deckert M, Schlüter D.
Institut für Medizinische Mikrobiologie, OvG Universität Magdeburg, Magdeburg, Germany.
The obligate intracellular parasite Toxoplasma gondii infects and persists within neurons of approximately one-third of the human population. Intracerebral control of T. gondii largely depends on interferon (IFN)-γ-producing T cells, which induce antiparasitic effector mechanisms in infected cells, as well as immunosuppressive cytokines, which prevent immunopathology. To gain further insight into the role of neurons in Toxoplasma encephalitis (TE), we generated C57BL/6 synapsin-I (Syn)-Cre gp130(fl/fl) mice, which lack gp130, the signal-transducing receptor for the IL-6 family of cytokines, in their neurons. On infection with T. gondii, Syn-Cre gp130(fl/fl) mice failed to control T. gondii infection and died of necrotizing TE before day 77. In contrast, gp130(fl/fl) control mice efficiently restricted parasite replication and survived the infection. TE in Syn-Cre gp130(fl/fl) mice was characterized by a hyperinflammatory immune response with increased numbers of IL-17- and IFN-γ-producing CD4 and CD8 T cells but reduced intracerebral production of immunosuppressive transforming growth factor (TGF)-β and IL-27. Additional in vitro experiments found that IL-6 stimulation of neurons induced gp130-dependent TGF-β1, TGF-β2, and IL-27 production. Importantly, gp130 expression and stimulation with IL-6 cytokine family members also reduced death and apoptosis of infected cultured neurons. Correspondingly, TE in Syn-Cre gp130(fl/fl) but not gp130(fl/fl) mice was characterized by progressive neuronal loss. Collectively, these findings indicate a crucial protective function of gp130-expressing neurons in a model of chronic encephalitis.
Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
PMID: 22640806 [PubMed - as supplied by publisher]
Neuronal gp130 Expression Is Crucial to Prevent Neuronal Loss, Hyperinflammation, and Lethal Course of Murine Toxoplasma Encephalitis
Händel U, Brunn A, Drögemüller K, Müller W, Deckert M, Schlüter D.
Institut für Medizinische Mikrobiologie, OvG Universität Magdeburg, Magdeburg, Germany.
The obligate intracellular parasite Toxoplasma gondii infects and persists within neurons of approximately one-third of the human population. Intracerebral control of T. gondii largely depends on interferon (IFN)-γ-producing T cells, which induce antiparasitic effector mechanisms in infected cells, as well as immunosuppressive cytokines, which prevent immunopathology. To gain further insight into the role of neurons in Toxoplasma encephalitis (TE), we generated C57BL/6 synapsin-I (Syn)-Cre gp130(fl/fl) mice, which lack gp130, the signal-transducing receptor for the IL-6 family of cytokines, in their neurons. On infection with T. gondii, Syn-Cre gp130(fl/fl) mice failed to control T. gondii infection and died of necrotizing TE before day 77. In contrast, gp130(fl/fl) control mice efficiently restricted parasite replication and survived the infection. TE in Syn-Cre gp130(fl/fl) mice was characterized by a hyperinflammatory immune response with increased numbers of IL-17- and IFN-γ-producing CD4 and CD8 T cells but reduced intracerebral production of immunosuppressive transforming growth factor (TGF)-β and IL-27. Additional in vitro experiments found that IL-6 stimulation of neurons induced gp130-dependent TGF-β1, TGF-β2, and IL-27 production. Importantly, gp130 expression and stimulation with IL-6 cytokine family members also reduced death and apoptosis of infected cultured neurons. Correspondingly, TE in Syn-Cre gp130(fl/fl) but not gp130(fl/fl) mice was characterized by progressive neuronal loss. Collectively, these findings indicate a crucial protective function of gp130-expressing neurons in a model of chronic encephalitis.
Copyright © 2012 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
PMID: 22640806 [PubMed - as supplied by publisher]
Sunday, May 27, 2012
Acute Encephalopathy in the Immune-compromised Child: Never Forget Toxoplasmosis
J Pediatr Hematol Oncol. 2012 May 22. [Epub ahead of print]
Acute Encephalopathy in the Immune-compromised Child: Never Forget Toxoplasmosis
Caselli D, Andreoli E, Paolicchi O, Savelli S, Guidi S, Pecile P, Aricò M.
Departments of *Pediatric Hematology Oncology ‡Pediatric Radiology, Azienda Ospedaliero-Universitaria Meyer †Laboratorio di Microbiologia e Virologia, Azienda Ospedaliero Universitaria §Department of Hematology, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
Toxoplasma gondii is an opportunistic parasite, which very unusually may cause acute encephalitis in patients undergoing chemotherapy or hematopoietic stem cell transplant. The prognosis is usually dismal also because of late diagnosis, depending on the limited availability of specific diagnostic tools. An early diagnosis allows effective intervention with specific antibiotics, which may provide a chance for cure. We report 2 cases of cerebral toxoplasmosis in which the use of polymerase chain reaction on cerebrospinal fluid allowed a prompt diagnosis and specific therapy, which was followed by clinical response and negativization at follow-up studies of T. gondii genome on cerebrospinal fluid by polymerase chain reaction and by brain imaging.
PMID: 22627571 [PubMed - as supplied by publisher]
Acute Encephalopathy in the Immune-compromised Child: Never Forget Toxoplasmosis
Caselli D, Andreoli E, Paolicchi O, Savelli S, Guidi S, Pecile P, Aricò M.
Departments of *Pediatric Hematology Oncology ‡Pediatric Radiology, Azienda Ospedaliero-Universitaria Meyer †Laboratorio di Microbiologia e Virologia, Azienda Ospedaliero Universitaria §Department of Hematology, Azienda Ospedaliero Universitaria Careggi, Florence, Italy.
Toxoplasma gondii is an opportunistic parasite, which very unusually may cause acute encephalitis in patients undergoing chemotherapy or hematopoietic stem cell transplant. The prognosis is usually dismal also because of late diagnosis, depending on the limited availability of specific diagnostic tools. An early diagnosis allows effective intervention with specific antibiotics, which may provide a chance for cure. We report 2 cases of cerebral toxoplasmosis in which the use of polymerase chain reaction on cerebrospinal fluid allowed a prompt diagnosis and specific therapy, which was followed by clinical response and negativization at follow-up studies of T. gondii genome on cerebrospinal fluid by polymerase chain reaction and by brain imaging.
PMID: 22627571 [PubMed - as supplied by publisher]
Friday, May 25, 2012
Foodborne Toxoplasmosis
Clin Infect Dis. 2012 May 22. [Epub ahead of print]
Foodborne Toxoplasmosis
Jones JL, Dubey JP.
Parasitic Diseases Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia.
Toxoplasmosis can be due to congenital infection or acquired infection after birth and is one of the leading illnesses associated with foodborne hospitalizations and deaths. Undercooked meat, especially pork, lamb, and wild game meat, and soil contaminated with cat feces on raw fruits and vegetables are the major sources of foodborne transmission for humans. The new trend in the production of free-range organically raised meat could increase the risk of Toxoplasma gondii contamination of meat. Foodborne transmission can be prevented by production practices that reduce T. gondii in meat, adequate cooking of meat, washing of raw fruits and vegetables, prevention of cross contamination in the kitchen, and measures that decrease spread of viable oocysts into the environment.
PMID: 22618566
Foodborne Toxoplasmosis
Jones JL, Dubey JP.
Parasitic Diseases Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia.
Toxoplasmosis can be due to congenital infection or acquired infection after birth and is one of the leading illnesses associated with foodborne hospitalizations and deaths. Undercooked meat, especially pork, lamb, and wild game meat, and soil contaminated with cat feces on raw fruits and vegetables are the major sources of foodborne transmission for humans. The new trend in the production of free-range organically raised meat could increase the risk of Toxoplasma gondii contamination of meat. Foodborne transmission can be prevented by production practices that reduce T. gondii in meat, adequate cooking of meat, washing of raw fruits and vegetables, prevention of cross contamination in the kitchen, and measures that decrease spread of viable oocysts into the environment.
PMID: 22618566
Wednesday, May 23, 2012
The HU protein is important for apicoplast genome maintenance and inheritance in Toxoplasma gondii
Eukaryot Cell. 2012 May 18. [Epub ahead of print]
The HU protein is important for apicoplast genome maintenance and inheritance in Toxoplasma gondii
Reiff SB, Vaishnava S, Striepen B.
Department of Cellular Biology.
The apicoplast, a chloroplast-like organelle, is an essential cellular component of most apicomplexan parasites including Plasmodium and Toxoplasma. The apicoplast maintains its own genome, a 35 kb DNA molecule that largely encodes proteins required for organellar transcription and translation. Interference with apicoplast genome maintenance and function is a validated target for drug therapy for malaria and toxoplasmosis. However, the many proteins required for genome maintenance and inheritance remain largely unstudied. Here we genetically characterize a nuclear encoded homolog to the bacterial-like HU protein in T. gondii. In bacteria HU is a DNA-binding structural protein with fundamental roles in transcription, replication initiation, and DNA repair. Immunofluorescence assays reveal that in T. gondii this protein localizes to the apicoplast. We have found that the HU protein from Toxoplasma can successfully complement bacterial ΔhupA mutants, supporting a similar function. We were able to construct a genetic knockout of HU in Toxoplasma. This Δhu mutant is barely viable and exhibits significant growth retardation. Upon further analysis of the mutant phenotype, we find that this mutant has a dramatically reduced apicoplast genome copy number, and furthermore suffers defects in the segregation of the apicoplast organelle. Our findings not only show that the HU protein is important for Toxoplasma cell biology, but also demonstrate the importance of the apicoplast genome in the biogenesis of the organelle.
PMID: 22611021
The HU protein is important for apicoplast genome maintenance and inheritance in Toxoplasma gondii
Reiff SB, Vaishnava S, Striepen B.
Department of Cellular Biology.
The apicoplast, a chloroplast-like organelle, is an essential cellular component of most apicomplexan parasites including Plasmodium and Toxoplasma. The apicoplast maintains its own genome, a 35 kb DNA molecule that largely encodes proteins required for organellar transcription and translation. Interference with apicoplast genome maintenance and function is a validated target for drug therapy for malaria and toxoplasmosis. However, the many proteins required for genome maintenance and inheritance remain largely unstudied. Here we genetically characterize a nuclear encoded homolog to the bacterial-like HU protein in T. gondii. In bacteria HU is a DNA-binding structural protein with fundamental roles in transcription, replication initiation, and DNA repair. Immunofluorescence assays reveal that in T. gondii this protein localizes to the apicoplast. We have found that the HU protein from Toxoplasma can successfully complement bacterial ΔhupA mutants, supporting a similar function. We were able to construct a genetic knockout of HU in Toxoplasma. This Δhu mutant is barely viable and exhibits significant growth retardation. Upon further analysis of the mutant phenotype, we find that this mutant has a dramatically reduced apicoplast genome copy number, and furthermore suffers defects in the segregation of the apicoplast organelle. Our findings not only show that the HU protein is important for Toxoplasma cell biology, but also demonstrate the importance of the apicoplast genome in the biogenesis of the organelle.
PMID: 22611021
Inhibition of increased indoleamine 2,3-dioxygenase activity attenuates Toxoplasma gondii replication in the lung during acute infection
Cytokine. 2012 May 18. [Epub ahead of print]
Inhibition of increased indoleamine 2,3-dioxygenase activity attenuates Toxoplasma gondii replication in the lung during acute infection
Murakami Y, Hoshi M, Hara A, Takemura M, Arioka Y, Yamamoto Y, Matsunami H, Funato T, Seishima M, Saito K.
Human Health Sciences, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto 606-8507, Japan.
The regulation of local l-tryptophan concentrations by tryptophan-degrading enzyme, indoleamine 2,3-dioxygenase (IDO) induced by various stimuli such as interferon-γ (IFN-γ) is one of the key mechanisms in antimicrobial effect. Recently, IDO is also focused on an immunosuppressive mechanism shared by several different immune cell types. Here, we show that inhibition of increased IDO activity maybe involved in the antiparasitic mechanism during Toxoplasma gondii (T. gondii) infection in vivo. In this study, we investigated the role of IDO by using IDO-gene-deficient (IDO KO) mice and by administering a competitive enzyme inhibitor, 1-methyl-d,l-tryptophan (1MT), to wild-type mice following T. gondii infection. Although depletion of lung l-tryptophan did not occur in IDO KO mice after T. gondii infection, the increased mRNA expression of T. gondii surface antigen gene 2 (SAG2) and the inflammatory cytokines in the lung were drastically reduced in the IDO KO mice following infection. We also found that complete depletion of lung l-tryptophan was observed in wild-type mice after infection, but not in mice treated with 1MT. At the same time, 1MT suppressed the increased mRNA expression of SAG2. Taken together, we observed that the inflammatory damage was significantly decreased by the administration of 1MT in the lung after infection. Inhibition of the IDO activity or the elimination of IDO's substrate may be an effective therapy against microbial diseases.
PMID: 22609210
Inhibition of increased indoleamine 2,3-dioxygenase activity attenuates Toxoplasma gondii replication in the lung during acute infection
Murakami Y, Hoshi M, Hara A, Takemura M, Arioka Y, Yamamoto Y, Matsunami H, Funato T, Seishima M, Saito K.
Human Health Sciences, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto 606-8507, Japan.
The regulation of local l-tryptophan concentrations by tryptophan-degrading enzyme, indoleamine 2,3-dioxygenase (IDO) induced by various stimuli such as interferon-γ (IFN-γ) is one of the key mechanisms in antimicrobial effect. Recently, IDO is also focused on an immunosuppressive mechanism shared by several different immune cell types. Here, we show that inhibition of increased IDO activity maybe involved in the antiparasitic mechanism during Toxoplasma gondii (T. gondii) infection in vivo. In this study, we investigated the role of IDO by using IDO-gene-deficient (IDO KO) mice and by administering a competitive enzyme inhibitor, 1-methyl-d,l-tryptophan (1MT), to wild-type mice following T. gondii infection. Although depletion of lung l-tryptophan did not occur in IDO KO mice after T. gondii infection, the increased mRNA expression of T. gondii surface antigen gene 2 (SAG2) and the inflammatory cytokines in the lung were drastically reduced in the IDO KO mice following infection. We also found that complete depletion of lung l-tryptophan was observed in wild-type mice after infection, but not in mice treated with 1MT. At the same time, 1MT suppressed the increased mRNA expression of SAG2. Taken together, we observed that the inflammatory damage was significantly decreased by the administration of 1MT in the lung after infection. Inhibition of the IDO activity or the elimination of IDO's substrate may be an effective therapy against microbial diseases.
PMID: 22609210
Toxoplasma Sortilin-like Receptor Regulates Protein Transport and Is Essential for Apical Secretory Organelle Biogenesis and Host Infection
Cell Host Microbe. 2012 May 17;11(5):515-27.
Toxoplasma Sortilin-like Receptor Regulates Protein Transport and Is Essential for Apical Secretory Organelle Biogenesis and Host Infection
Sloves PJ, Delhaye S, Mouveaux T, Werkmeister E, Slomianny C, Hovasse A, Dilezitoko Alayi T, Callebaut I, Gaji RY, Schaeffer-Reiss C, Van Dorsselear A, Carruthers VB, Tomavo S.
Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, 59000 Lille, France.
Apicomplexan parasites have an assortment of unique apical secretory organelles (rhoptries and micronemes), which have crucial functions in host infection. Here, we show that a Toxoplasma gondii sortilin-like receptor (TgSORTLR) is required for the subcellular localization and formation of apical secretory organelles. TgSORTLR is a transmembrane protein that resides within Golgi-endosomal related compartments. The lumenal domain specifically interacts with rhoptry and microneme proteins, while the cytoplasmic tail of TgSORTLR recruits cytosolic sorting machinery involved in anterograde and retrograde protein transport. Ectopic expression of the N-terminal TgSORTLR lumenal domain results in dominant negative effects with the mislocalization of both endogenous TgSORTLR as well as rhoptry and microneme proteins. Conditional ablation of TgSORTLR disrupts rhoptry and microneme biogenesis, inhibits parasite motility, and blocks both invasion into and egress from host cells. Thus, the sortilin-like receptor is essential for protein trafficking and the biogenesis of key secretory organelles in Toxoplasma.
PMID: 22607804
Toxoplasma Sortilin-like Receptor Regulates Protein Transport and Is Essential for Apical Secretory Organelle Biogenesis and Host Infection
Sloves PJ, Delhaye S, Mouveaux T, Werkmeister E, Slomianny C, Hovasse A, Dilezitoko Alayi T, Callebaut I, Gaji RY, Schaeffer-Reiss C, Van Dorsselear A, Carruthers VB, Tomavo S.
Center for Infection and Immunity of Lille, CNRS UMR 8204, INSERM U 1019, Institut Pasteur de Lille, Université Lille Nord de France, 59000 Lille, France.
Apicomplexan parasites have an assortment of unique apical secretory organelles (rhoptries and micronemes), which have crucial functions in host infection. Here, we show that a Toxoplasma gondii sortilin-like receptor (TgSORTLR) is required for the subcellular localization and formation of apical secretory organelles. TgSORTLR is a transmembrane protein that resides within Golgi-endosomal related compartments. The lumenal domain specifically interacts with rhoptry and microneme proteins, while the cytoplasmic tail of TgSORTLR recruits cytosolic sorting machinery involved in anterograde and retrograde protein transport. Ectopic expression of the N-terminal TgSORTLR lumenal domain results in dominant negative effects with the mislocalization of both endogenous TgSORTLR as well as rhoptry and microneme proteins. Conditional ablation of TgSORTLR disrupts rhoptry and microneme biogenesis, inhibits parasite motility, and blocks both invasion into and egress from host cells. Thus, the sortilin-like receptor is essential for protein trafficking and the biogenesis of key secretory organelles in Toxoplasma.
PMID: 22607804
Tuesday, May 22, 2012
POSTDOCTORAL POSITIONS: Dr. Silvia Moreno
POSTDOCTORAL POSITIONS AVAILABLE: Dr. Silvia Moreno
UNIVERSITY OF GEORGIA
Our laboratory recently discovered a novel post-Golgi compartment in Toxoplasma gondii that we named as plant-like vacuole (PLV) because of its similarities to the plant vacuole both in composition and function (Mol. Microbiol., 76:1358, 2010). We are now interested in studying the role of this organelle in the biology of the parasite. The PLV appears to be linked to the endocytic/exocytic pathway of the parasite and we think that it plays a central role during the extracellular phase of the parasite not only in resisting environmental stress but also as it prepares itself for invading the next host cell. We are interested in the role of the PLV in calcium homeostasis and other ionic stresses and also its role in sorting of protein to other important secretory organelles. We have a large number of genetic tools available to use to respond to biochemical and physiological questions. Check our web site for more information about our program.
Position 2
Our laboratory is interested in the characterization of calcium homeostasis in Toxoplasma gondii, an intracellular pathogen of humans and animals. Strong evidence shows that calcium plays a critical role in T. gondii virulence and very little is known of the molecular mechanisms involved. Previous work from our laboratory characterized calcium rich acidic compartments in T. gondii and other protozoan parasites (Nature Rev. 3:251, 2005). Presently we are studying the role of extracellular calcium in parasite virulence and how acidic stores regulate calcium entry. We are specially interested in finding the molecular players involved, which appear to be different from those of mammalian cells. Our laboratory uses a variety of genetic tools and reagents available in our community to answer biochemical and physiological questions. Check our web site for more information.
The Center for Tropical and Emerging Global Diseases (CTEGD) is an interdisciplinary center established to foster research, educational programs and service related to tropical and emerging diseases. The Center is made up of a wide range of research programs that focus on the immunology, biochemistry and molecular and cell biology of protozoan and metazoan parasites.
Athens, Georgia is an excellent place to live. It is a small college town with a vibrant downtown nightlife, excellent restaurants, nearby mountains and rivers, and a very reasonable cost of living (http://www.visitathensga.com/).
Applicants interested in joining this exciting program send a CV and names of three references to: Silvia N.J. Moreno, smoreno@uga.edu.
Wednesday, May 16, 2012
Biochemical and molecular characterization of the pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase from Toxoplasma gondii
Mol Biochem Parasitol. 2012 May 8. [Epub ahead of print]
Biochemical and molecular characterization of the pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase from Toxoplasma gondii
Triana MA, Huynh MH, Garavito MF, Fox BA, Bzik DJ, Carruthers VB, Löffler M, Zimmermann BH.
Departamento de Ciencias Biologicas, Universidad de los Andes, Carrera 1, No. 18A-10, Bogotá, Colombia.
The pyrimidine biosynthesis pathway in the protozoan pathogen Toxoplasma gondii is essential for parasite growth during infection. To investigate the properties of dihydroorotate dehydrogenase (TgDHOD), the fourth enzyme in the T. gondii pyrimidine pathway, we expressed and purified recombinant TgDHOD. TgDHOD exhibited a specific activity of 84 U/mg, a k(cat) of 89 sec(-1), a K(m)=60μM for L-dihydroorotate, and a K(m)=29μM for decylubiquinone (Q(D)). Quinones lacking or having short isoprenoid side chains yielded lower k(cat)s than Q(D). As expected, fumarate was a poor electron acceptor for this family 2 DHOD. The The IC(50)s determined for A77-1726, the active derivative of the human DHOD inhibitor leflunomide, and related compounds MD249 and MD209 were, 91μM, 96μM, and 60μM, respectively. The enzyme was not significantly affected by brequinar or TTFA, known inhibitors of human DHOD, or by atovaquone. DSM190, a known inhibitor of Plasmodium falciparum DHOD, was a poor inhibitor of TgDHOD. TgDHOD exhibits a lengthy 157-residue N-terminal extension, consistent with a potential organellar targeting signal. We constructed C-terminally c-myc tagged TgDHODs to examine subcellular localization of TgDHOD in transgenic parasites expressing the tagged protein. Using both exogenous and endogenous expression strategies, anti-myc fluorescence signal colocalized with antibodies against the mitochondrial marker ATPase. These findings demonstrate that TgDHOD is associated with the parasite's mitochondrion, revealing this organelle as the site of orotate production in T. gondii. The TgDHOD gene appears to be essential because while gene tagging was successful at the TgDHOD gene locus, attempts to delete the TgDHOD gene were not successful in the KU80 background. Collectively, our study suggests that TgDHOD is an excellent target for the development of anti-Toxoplasma drugs.
Copyright © 2012. Published by Elsevier B.V.
PMID: 22580100 [PubMed - as supplied by publisher]
Biochemical and molecular characterization of the pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase from Toxoplasma gondii
Triana MA, Huynh MH, Garavito MF, Fox BA, Bzik DJ, Carruthers VB, Löffler M, Zimmermann BH.
Departamento de Ciencias Biologicas, Universidad de los Andes, Carrera 1, No. 18A-10, Bogotá, Colombia.
The pyrimidine biosynthesis pathway in the protozoan pathogen Toxoplasma gondii is essential for parasite growth during infection. To investigate the properties of dihydroorotate dehydrogenase (TgDHOD), the fourth enzyme in the T. gondii pyrimidine pathway, we expressed and purified recombinant TgDHOD. TgDHOD exhibited a specific activity of 84 U/mg, a k(cat) of 89 sec(-1), a K(m)=60μM for L-dihydroorotate, and a K(m)=29μM for decylubiquinone (Q(D)). Quinones lacking or having short isoprenoid side chains yielded lower k(cat)s than Q(D). As expected, fumarate was a poor electron acceptor for this family 2 DHOD. The The IC(50)s determined for A77-1726, the active derivative of the human DHOD inhibitor leflunomide, and related compounds MD249 and MD209 were, 91μM, 96μM, and 60μM, respectively. The enzyme was not significantly affected by brequinar or TTFA, known inhibitors of human DHOD, or by atovaquone. DSM190, a known inhibitor of Plasmodium falciparum DHOD, was a poor inhibitor of TgDHOD. TgDHOD exhibits a lengthy 157-residue N-terminal extension, consistent with a potential organellar targeting signal. We constructed C-terminally c-myc tagged TgDHODs to examine subcellular localization of TgDHOD in transgenic parasites expressing the tagged protein. Using both exogenous and endogenous expression strategies, anti-myc fluorescence signal colocalized with antibodies against the mitochondrial marker ATPase. These findings demonstrate that TgDHOD is associated with the parasite's mitochondrion, revealing this organelle as the site of orotate production in T. gondii. The TgDHOD gene appears to be essential because while gene tagging was successful at the TgDHOD gene locus, attempts to delete the TgDHOD gene were not successful in the KU80 background. Collectively, our study suggests that TgDHOD is an excellent target for the development of anti-Toxoplasma drugs.
Copyright © 2012. Published by Elsevier B.V.
PMID: 22580100 [PubMed - as supplied by publisher]
Saturday, May 12, 2012
ApicoAP: The First Computational Model for Identifying Apicoplast-Targeted Proteins in Multiple Species of Apicomplexa
PLoS One. 2012;7(5):e36598. Epub 2012 May 4.
ApicoAP: The First Computational Model for Identifying Apicoplast-Targeted Proteins in Multiple Species of Apicomplexa
Cilingir G, Broschat SL, Lau AO.
School of Electrical Engineering and Computer Science, Washington State University, Pullman, Washington, United States of America.
BACKGROUND:
Most of the parasites of the phylum Apicomplexa contain a relict prokaryotic-derived plastid called the apicoplast. This organelle is important not only for the survival of the parasite, but its unique properties make it an ideal drug target. The majority of apicoplast-associated proteins are nuclear encoded and targeted post-translationally to the organellar lumen via a bipartite signaling mechanism that requires an N-terminal signal and transit peptide (TP). Attempts to define a consensus motif that universally identifies apicoplast TPs have failed.
METHODOLOGY/PRINCIPAL FINDINGS:
In this study, we propose a generalized rule-based classification model to identify apicoplast-targeted proteins (ApicoTPs) that use a bipartite signaling mechanism. Given a training set specific to an organism, this model, called ApicoAP, incorporates a procedure based on a genetic algorithm to tailor a discriminating rule that exploits the known characteristics of ApicoTPs. Performance of ApicoAP is evaluated for four labeled datasets of Plasmodium falciparum, Plasmodium yoelii, Babesia bovis, and Toxoplasma gondii proteins. ApicoAP improves the classification accuracy of the published dataset for P. falciparum to 94%, originally 90% using PlasmoAP.
CONCLUSIONS/SIGNIFICANCE:
We present a parametric model for ApicoTPs and a procedure to optimize the model parameters for a given training set. A major asset of this model is that it is customizable to different parasite genomes. The ApicoAP prediction software is available at http://code.google.com/p/apicoap/ and http://bcb.eecs.wsu.edu.
PMID: 22574192 [PubMed - in process]
ApicoAP: The First Computational Model for Identifying Apicoplast-Targeted Proteins in Multiple Species of Apicomplexa
Cilingir G, Broschat SL, Lau AO.
School of Electrical Engineering and Computer Science, Washington State University, Pullman, Washington, United States of America.
BACKGROUND:
Most of the parasites of the phylum Apicomplexa contain a relict prokaryotic-derived plastid called the apicoplast. This organelle is important not only for the survival of the parasite, but its unique properties make it an ideal drug target. The majority of apicoplast-associated proteins are nuclear encoded and targeted post-translationally to the organellar lumen via a bipartite signaling mechanism that requires an N-terminal signal and transit peptide (TP). Attempts to define a consensus motif that universally identifies apicoplast TPs have failed.
METHODOLOGY/PRINCIPAL FINDINGS:
In this study, we propose a generalized rule-based classification model to identify apicoplast-targeted proteins (ApicoTPs) that use a bipartite signaling mechanism. Given a training set specific to an organism, this model, called ApicoAP, incorporates a procedure based on a genetic algorithm to tailor a discriminating rule that exploits the known characteristics of ApicoTPs. Performance of ApicoAP is evaluated for four labeled datasets of Plasmodium falciparum, Plasmodium yoelii, Babesia bovis, and Toxoplasma gondii proteins. ApicoAP improves the classification accuracy of the published dataset for P. falciparum to 94%, originally 90% using PlasmoAP.
CONCLUSIONS/SIGNIFICANCE:
We present a parametric model for ApicoTPs and a procedure to optimize the model parameters for a given training set. A major asset of this model is that it is customizable to different parasite genomes. The ApicoAP prediction software is available at http://code.google.com/p/apicoap/ and http://bcb.eecs.wsu.edu.
PMID: 22574192 [PubMed - in process]
Inhibition of p-aminobenzoate and folate syntheses in plants and apicomplexan parasites by the natural product rubreserine
J Biol Chem. 2012 May 10. [Epub ahead of print]
Inhibition of p-aminobenzoate and folate syntheses in plants and apicomplexan parasites by the natural product rubreserine
Camara D, Bisanz C, Barette C, Van Daele J, Human E, Barnard B, Van Der Straeten D, Stove CP, Lambert WE, Douce R, Marechal E, Birkholtz LM, Cesbron-Delauw MF, Dumas R, Rebeille F.
CEA-Grenoble, France;
Glutamine amidotransferase / aminodeoxychorismate synthase (GAT-ADCS) is a bifunctional enzyme involved in the synthesis of p-aminobenzoate (pABA), a central component part of folate cofactors. GAT-ADCS is found in eukaryotic organisms autonomous for folate biosynthesis, such as plants or parasites of the phylum Apicomplexa. Based on an automated screening to search for new inhibitors of folate biosynthesis, we found that rubreserine was able to inhibit the GAT activity of the plant GAT-ADCS with an apparent IC50 of about 8 micromolar. The growth rates of Arabidopsis thaliana, Toxoplasma gondii and Plasmodium falciparum were inhibited by rubreserine with respective IC50 values of 65, 20 and 1 micromolar. The correlation between folate biosynthesis and growth inhibition was studied with Arabidopsis and Toxoplasma. In both organisms the folate content was decreased by 40 - 50 % in the presence of rubreserine. In both organisms, the addition of pABA or 5-formyltetrahydrofolate in the external medium restored the growth for inhibitor concentrations up to the IC50 value, indicating that, within this range of concentrations, rubreserine was specific for folate biosynthesis. Rubreserine appeared to be more efficient than sulfonamides, antifolate drugs known to inhibit the invasion and proliferation of Toxoplasma gondii in human fibroblasts. Altogether, these results validate the use of the bifunctional GAT-ADCS as an efficient drug target in eukaryotic cells, and indicate that the chemical structure of rubreserine presents interesting anti-parasitic (toxoplasmosis, malaria) potential.
PMID: 22577137 [PubMed - as supplied by publisher]
Inhibition of p-aminobenzoate and folate syntheses in plants and apicomplexan parasites by the natural product rubreserine
Camara D, Bisanz C, Barette C, Van Daele J, Human E, Barnard B, Van Der Straeten D, Stove CP, Lambert WE, Douce R, Marechal E, Birkholtz LM, Cesbron-Delauw MF, Dumas R, Rebeille F.
CEA-Grenoble, France;
Glutamine amidotransferase / aminodeoxychorismate synthase (GAT-ADCS) is a bifunctional enzyme involved in the synthesis of p-aminobenzoate (pABA), a central component part of folate cofactors. GAT-ADCS is found in eukaryotic organisms autonomous for folate biosynthesis, such as plants or parasites of the phylum Apicomplexa. Based on an automated screening to search for new inhibitors of folate biosynthesis, we found that rubreserine was able to inhibit the GAT activity of the plant GAT-ADCS with an apparent IC50 of about 8 micromolar. The growth rates of Arabidopsis thaliana, Toxoplasma gondii and Plasmodium falciparum were inhibited by rubreserine with respective IC50 values of 65, 20 and 1 micromolar. The correlation between folate biosynthesis and growth inhibition was studied with Arabidopsis and Toxoplasma. In both organisms the folate content was decreased by 40 - 50 % in the presence of rubreserine. In both organisms, the addition of pABA or 5-formyltetrahydrofolate in the external medium restored the growth for inhibitor concentrations up to the IC50 value, indicating that, within this range of concentrations, rubreserine was specific for folate biosynthesis. Rubreserine appeared to be more efficient than sulfonamides, antifolate drugs known to inhibit the invasion and proliferation of Toxoplasma gondii in human fibroblasts. Altogether, these results validate the use of the bifunctional GAT-ADCS as an efficient drug target in eukaryotic cells, and indicate that the chemical structure of rubreserine presents interesting anti-parasitic (toxoplasmosis, malaria) potential.
PMID: 22577137 [PubMed - as supplied by publisher]
Thursday, May 10, 2012
The obligate intracellular parasite Toxoplasma gondii secretes a soluble phosphatidylserine decarboxylase
J Biol Chem. 2012 May 4. [Epub ahead of print]
The obligate intracellular parasite Toxoplasma gondii secretes a soluble phosphatidylserine decarboxylase
Gupta N, Hartmann A, Lucius R, Voelker DR.
Humboldt University, Germany;
Toxoplasma gondii is an obligate intracellular parasite capable of causing fatal infections in immunocompromised individuals and neonates. Examination of the phosphatidylserine (PtdSer) metabolism of T. gondii reveals that the parasite secretes a soluble form of PtdSer decarboxylase (TgPSD1), which preferentially decarboxylates liposomal PtdSer with an apparent K( m) of 67 μM. The specific enzyme activity increases by 3-fold during the replication of T. gondii, and soluble PSD accounts for ~20% of the total PSD, prior to the parasite egress from host cells. Extracellular T. gondii secreted ~20% of its total PSD activity at 37°C, and the intracellular Ca(++) chelator BAPTA-AM inhibited the process by 50%. Cycloheximide, Brefeldin A, ionic composition of the medium and exogenous PtdSer did not modulate the enzyme secretion, which suggests a constitutive discharge of a presynthesized pool of PSD in axenic T. gondii. TgPSD1 consists of 968 residues with a 26-amino acid hydrophobic peptide at the N-terminus, and no predicted membrane-domain. Parasites over-expressing TgPSD1-HA secreted 10-fold more activity compared to the parental strain. Exposure of apoptotic Jurkat cells to transgenic parasites demonstrated interfacial catalysis by secreted TgPSD1 that reduced host cell surface expression of PtdSer. Immuno-localization experiments revealed that TgPSD1 resides in the dense granules of T. gondii and is also found in the parasitophorous vacuole of replicating parasites. Together, these findings demonstrate novel features of the parasite enzyme since a secreted, soluble and interfacially active form of PSD has not been previously described for any organism.
PMID: 22563079 [PubMed - as supplied by publisher]
The obligate intracellular parasite Toxoplasma gondii secretes a soluble phosphatidylserine decarboxylase
Gupta N, Hartmann A, Lucius R, Voelker DR.
Humboldt University, Germany;
Toxoplasma gondii is an obligate intracellular parasite capable of causing fatal infections in immunocompromised individuals and neonates. Examination of the phosphatidylserine (PtdSer) metabolism of T. gondii reveals that the parasite secretes a soluble form of PtdSer decarboxylase (TgPSD1), which preferentially decarboxylates liposomal PtdSer with an apparent K( m) of 67 μM. The specific enzyme activity increases by 3-fold during the replication of T. gondii, and soluble PSD accounts for ~20% of the total PSD, prior to the parasite egress from host cells. Extracellular T. gondii secreted ~20% of its total PSD activity at 37°C, and the intracellular Ca(++) chelator BAPTA-AM inhibited the process by 50%. Cycloheximide, Brefeldin A, ionic composition of the medium and exogenous PtdSer did not modulate the enzyme secretion, which suggests a constitutive discharge of a presynthesized pool of PSD in axenic T. gondii. TgPSD1 consists of 968 residues with a 26-amino acid hydrophobic peptide at the N-terminus, and no predicted membrane-domain. Parasites over-expressing TgPSD1-HA secreted 10-fold more activity compared to the parental strain. Exposure of apoptotic Jurkat cells to transgenic parasites demonstrated interfacial catalysis by secreted TgPSD1 that reduced host cell surface expression of PtdSer. Immuno-localization experiments revealed that TgPSD1 resides in the dense granules of T. gondii and is also found in the parasitophorous vacuole of replicating parasites. Together, these findings demonstrate novel features of the parasite enzyme since a secreted, soluble and interfacially active form of PSD has not been previously described for any organism.
PMID: 22563079 [PubMed - as supplied by publisher]
Triplex PCR using new primers for the detection of Toxoplasma gondii
Exp Parasitol. 2012 Apr 25. [Epub ahead of print]
Triplex PCR using new primers for the detection of Toxoplasma gondii
Rahumatullah A, Yin KB, Noordin R.
Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia
Molecular methods are used increasingly for the detection of Toxoplasma gondii infection. This study developed a rapid, sensitive, and specific conventional triplex PCR for the detection of the B1 gene and ITS1 region of T. gondii using newly designed primers and an internal control based on the Vibrio cholerae HemM gene. The annealing temperature and concentrations of the primers, MgCl(2), and dNTPs were optimized. Two sets of primers (set 1 and 2) were tested, which contained different segments of the T. gondii B1 gene, 529 repeat region and ITS1 region. A series of sensitivity tests were performed using parasite DNA, whole parasites, and spiked human body fluids. Specificity tests were performed using DNA from common protozoa and bacteria. The newly developed assay based on set 2 primers was found to be specific and sensitive. The test was capable of detecting as little as 10pg T. gondii DNA, 10(4) tachyzoites in spiked body fluids, and T. gondii DNA in the organ tissues of experimentally infected mice. The assay developed in this study will be useful for the laboratory detection of T. gondii infection.
Copyright © 2012 Elsevier Inc. All rights reserved.
PMID: 22561042 [PubMed - as supplied by publisher]
Triplex PCR using new primers for the detection of Toxoplasma gondii
Rahumatullah A, Yin KB, Noordin R.
Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia
Molecular methods are used increasingly for the detection of Toxoplasma gondii infection. This study developed a rapid, sensitive, and specific conventional triplex PCR for the detection of the B1 gene and ITS1 region of T. gondii using newly designed primers and an internal control based on the Vibrio cholerae HemM gene. The annealing temperature and concentrations of the primers, MgCl(2), and dNTPs were optimized. Two sets of primers (set 1 and 2) were tested, which contained different segments of the T. gondii B1 gene, 529 repeat region and ITS1 region. A series of sensitivity tests were performed using parasite DNA, whole parasites, and spiked human body fluids. Specificity tests were performed using DNA from common protozoa and bacteria. The newly developed assay based on set 2 primers was found to be specific and sensitive. The test was capable of detecting as little as 10pg T. gondii DNA, 10(4) tachyzoites in spiked body fluids, and T. gondii DNA in the organ tissues of experimentally infected mice. The assay developed in this study will be useful for the laboratory detection of T. gondii infection.
Copyright © 2012 Elsevier Inc. All rights reserved.
PMID: 22561042 [PubMed - as supplied by publisher]
Thursday, May 03, 2012
Toxoplasma gondii sexual cross in a single naturally infected feline host
Vet Res. 2012 Apr 30;43(1):39. [Epub ahead of print]
Toxoplasma gondii sexual cross in a single naturally infected feline host: generation of highly mouse-virulent and avirulent clones, genotypically different from clonal types I, II and III
Herrmann DC, Bärwald A, Maksimov A, Pantchev N, Vrhovec MG, Conraths FJ, Schares G.
ABSTRACT: Tachyzoite clones obtained from a single Toxoplasma gondii oocyst field sample were genotyped and characterized regarding mouse virulence. PCR-RFLP genotyping of tachyzoites initially isolated from interferon-gamma-knockout (GKO) mice, BALB/c mice and VERO cell culture using the nine independent, unlinked genetic markers nSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico revealed mixed T. gondii infections showing combinations of type II and type III alleles at different loci. Forty-five individual clones were obtained from all mixed T. gondii tachyzoite cell cultures by limiting dilution. Sixteen T. gondii clones showed type III alleles at all loci and 29 clones displayed a combination of type II and type III alleles at different loci. Five clone groups were identified in total, four of which include T. gondii clones that showed a non-canonical allele pattern and have never been described in natural infections before. All tested clones, except two, were highly virulent in BALB/c mice. The isolation of different non-canonical T. gondii clones originating from an oocyst sample of a single naturally infected cat demonstrate that sexual recombination as well as re-assortment of chromosomes via a sexual cross of T. gondii occur under natural conditions and result in the emergence of clones with increased virulence in mice.
PMID: 22546040 [PubMed - as supplied by publisher]
Toxoplasma gondii sexual cross in a single naturally infected feline host: generation of highly mouse-virulent and avirulent clones, genotypically different from clonal types I, II and III
Herrmann DC, Bärwald A, Maksimov A, Pantchev N, Vrhovec MG, Conraths FJ, Schares G.
ABSTRACT: Tachyzoite clones obtained from a single Toxoplasma gondii oocyst field sample were genotyped and characterized regarding mouse virulence. PCR-RFLP genotyping of tachyzoites initially isolated from interferon-gamma-knockout (GKO) mice, BALB/c mice and VERO cell culture using the nine independent, unlinked genetic markers nSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico revealed mixed T. gondii infections showing combinations of type II and type III alleles at different loci. Forty-five individual clones were obtained from all mixed T. gondii tachyzoite cell cultures by limiting dilution. Sixteen T. gondii clones showed type III alleles at all loci and 29 clones displayed a combination of type II and type III alleles at different loci. Five clone groups were identified in total, four of which include T. gondii clones that showed a non-canonical allele pattern and have never been described in natural infections before. All tested clones, except two, were highly virulent in BALB/c mice. The isolation of different non-canonical T. gondii clones originating from an oocyst sample of a single naturally infected cat demonstrate that sexual recombination as well as re-assortment of chromosomes via a sexual cross of T. gondii occur under natural conditions and result in the emergence of clones with increased virulence in mice.
PMID: 22546040 [PubMed - as supplied by publisher]
Toxoplasmosis in cord blood transplantation recipients
Transpl Infect Dis. 2012 May 1. doi: 10.1111/j.1399-3062.2012.00735.x. [Epub ahead of print]
Toxoplasmosis in cord blood transplantation recipients
Bautista G, Ramos A, Forés R, Regidor C, Ruiz E, de Laiglesia A, Navarro B, Bravo J, Portero F, Sanjuan I, Fernández MN, Cabrera R.
Department of Hematology, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain.
Toxoplasmosis is a devastating opportunistic infection that can affect immunocompromised patients such as cord blood transplantation (CBT) recipients. The clinical characteristics of 4 toxoplasmosis CBT patients treated at our institution are reviewed, together with 5 cases collected from the literature. The rate of toxoplasmosis in our hospital was 6% in CBT recipients and 0.2% in other types of allogeneic hematopoietic stem cell transplantation (P < 0.001). Five patients (56%) presented disseminated toxoplasmosis and 4 patients (44%) had localized infection in the central nervous system. In 5 of the 9 patients considered (56%), cytomegalovirus viral replication had been detected before the clinical onset of toxoplasmosis. Seven patients (78%) had previously developed graft-versus-host disease. All patients who exhibited disseminated disease died due to Toxoplasma infection. Pre-transplant serology was positive in 1 patient, negative in 3 patients, and not performed in another. Only 1 of these 5 patients with disseminated disease had received Toxoplasma prophylaxis with cotrimoxazole. It could be concluded that mortality in CBT patients with disseminated toxoplasmosis is unacceptably high. The negative results of serology in the majority of these cases, and its unspecific clinical presentation, makes diagnosis exceedingly difficult. Better diagnostic tests and prophylaxis strategy are needed in CBT recipients.
© 2012 John Wiley & Sons A/S.
PMID: 22548804 [PubMed - as supplied by publisher]
Toxoplasmosis in cord blood transplantation recipients
Bautista G, Ramos A, Forés R, Regidor C, Ruiz E, de Laiglesia A, Navarro B, Bravo J, Portero F, Sanjuan I, Fernández MN, Cabrera R.
Department of Hematology, Hospital Universitario Puerta de Hierro, Majadahonda, Madrid, Spain.
Toxoplasmosis is a devastating opportunistic infection that can affect immunocompromised patients such as cord blood transplantation (CBT) recipients. The clinical characteristics of 4 toxoplasmosis CBT patients treated at our institution are reviewed, together with 5 cases collected from the literature. The rate of toxoplasmosis in our hospital was 6% in CBT recipients and 0.2% in other types of allogeneic hematopoietic stem cell transplantation (P < 0.001). Five patients (56%) presented disseminated toxoplasmosis and 4 patients (44%) had localized infection in the central nervous system. In 5 of the 9 patients considered (56%), cytomegalovirus viral replication had been detected before the clinical onset of toxoplasmosis. Seven patients (78%) had previously developed graft-versus-host disease. All patients who exhibited disseminated disease died due to Toxoplasma infection. Pre-transplant serology was positive in 1 patient, negative in 3 patients, and not performed in another. Only 1 of these 5 patients with disseminated disease had received Toxoplasma prophylaxis with cotrimoxazole. It could be concluded that mortality in CBT patients with disseminated toxoplasmosis is unacceptably high. The negative results of serology in the majority of these cases, and its unspecific clinical presentation, makes diagnosis exceedingly difficult. Better diagnostic tests and prophylaxis strategy are needed in CBT recipients.
© 2012 John Wiley & Sons A/S.
PMID: 22548804 [PubMed - as supplied by publisher]
Wednesday, May 02, 2012
Lysine acetylation is widespread on proteins of diverse function and localization in the protozoan parasite Toxoplasma gondii
Eukaryot Cell. 2012 Apr 27. [Epub ahead of print]
Lysine acetylation is widespread on proteins of diverse function and localization in the protozoan parasite Toxoplasma gondii
Jeffers V, Sullivan WJ Jr.
Department of Pharmacology and Toxicology. Indiana University School of Medicine.
While histone proteins are the founding members of lysine acetylation substrates, it is now clear that hundreds of other proteins can be acetylated in multiple compartments of the cell. Our knowledge of the scope of this modification throughout the kingdom of life is beginning to emerge as proteome-wide lysine acetylation has been documented in prokaryotes, Arabidopsis thaliana, Drosophila melanogaster, and human cells. Using LC-MS/MS to identify parasite peptides enriched by immunopurification with acetyl-lysine antibody, we produced the first proteome-wide analysis of acetylation for a protozoan organism, the opportunistic apicomplexan parasite Toxoplasma gondii. The results show that lysine acetylation is abundant in the actively proliferating tachyzoite form of the parasite, which causes acute toxoplasmosis. Our approach successfully identified known acetylation marks on Toxoplasma histones and α-tubulin, and detected over 400 novel acetylation sites on a wide variety of additional proteins, including those with roles in transcription, translation, metabolism, and stress responses. Importantly, an extensive set of parasite-specific proteins are acetylated in the parasite, including those found in organelles unique to Apicomplexa. Our data provide a wealth of new information that improves our understanding of the evolution of this vital regulatory modification while potentially revealing novel therapeutic avenues. We conclude from this study that lysine acetylation was prevalent in the early stages of eukaryotic cell evolution and occurs on proteins involved in a remarkably diverse array of cellular functions, including those that are specific to parasites.
PMID: 22544907 [PubMed - as supplied by publisher]
Lysine acetylation is widespread on proteins of diverse function and localization in the protozoan parasite Toxoplasma gondii
Jeffers V, Sullivan WJ Jr.
Department of Pharmacology and Toxicology. Indiana University School of Medicine.
While histone proteins are the founding members of lysine acetylation substrates, it is now clear that hundreds of other proteins can be acetylated in multiple compartments of the cell. Our knowledge of the scope of this modification throughout the kingdom of life is beginning to emerge as proteome-wide lysine acetylation has been documented in prokaryotes, Arabidopsis thaliana, Drosophila melanogaster, and human cells. Using LC-MS/MS to identify parasite peptides enriched by immunopurification with acetyl-lysine antibody, we produced the first proteome-wide analysis of acetylation for a protozoan organism, the opportunistic apicomplexan parasite Toxoplasma gondii. The results show that lysine acetylation is abundant in the actively proliferating tachyzoite form of the parasite, which causes acute toxoplasmosis. Our approach successfully identified known acetylation marks on Toxoplasma histones and α-tubulin, and detected over 400 novel acetylation sites on a wide variety of additional proteins, including those with roles in transcription, translation, metabolism, and stress responses. Importantly, an extensive set of parasite-specific proteins are acetylated in the parasite, including those found in organelles unique to Apicomplexa. Our data provide a wealth of new information that improves our understanding of the evolution of this vital regulatory modification while potentially revealing novel therapeutic avenues. We conclude from this study that lysine acetylation was prevalent in the early stages of eukaryotic cell evolution and occurs on proteins involved in a remarkably diverse array of cellular functions, including those that are specific to parasites.
PMID: 22544907 [PubMed - as supplied by publisher]
Oocyst shedding in cats vaccinated by the nasal and rectal routes with crude rhoptry proteins of Toxoplasma gondii
Exp Parasitol. 2012 Apr 19. [Epub ahead of print]
Oocyst shedding in cats vaccinated by the nasal and rectal routes with crude rhoptry proteins of Toxoplasma gondii
Zulpo DL, Headley SA, Biazzono L, da Cunha IA, Igarashi M, de Barros LD, Taroda A, Cardim ST, Bogado AL, Navarro IT, Garcia JL.
Protozoology Laboratory, Departamento de Medicina Veterinária Preventiva, Universidade de Londrina-UEL, P.O. Box 6001, 86050-970 Londrina, PR, Brazil.
During this study, cats were immunized by the intranasal and rectal routes with crude rhoptry proteins of Toxoplasma gondii admixed with Quil-A. Twenty-five domestic short hair cats divided into five groups (n=5) were used during this evaluation: G1 and G3 cats received 200μg of the rhoptry proteins with Quil-A (20μg) by the intranasal and rectal routes, respectively; G2 and G4 cats received bovine serum albumin (BSA, 200μg/dose) with Quil-A (20μg); and G5 animals served as unvaccinated controls. All treatments were performed at days 0, 21, 42, and 63. The challenge was done with 800 cysts of the ME49 of T. gondii strain at day 70 (challenge day). The serum IgG, IgM, IgA, and fecal IgA antibody levels were evaluated by using the indirect enzyme-linked immunosorbent assay (ELISA). Some animals produced antibody levels beyond cut-off; however, two animals from G1 (OD(mean)=0.308, OD(cut-off)=0.200) and three from G3 (OD(mean)=0.254) demonstrated IgG levels on being challenged, with similar results occurring in two cats from G1 to IgM (OD(mean)=0.279, OD(cut-off)=0.200). Fecal IgA levels were detected in all G1 cats (OD(mean)=0.330, OD(cut-off)=0.065), and in one cat from G3 (OD(mean)=0.167). The serum and fecal humoral immune responses did not correlate with oocyst shedding. Oocyst shedding varied from 98.4% (G1), 87.5% (G2), 53.0% (G3), to 58% (G4), and was lower than that of G5 cats. The prepatent period of cats vaccinated intranasally (G1) was reduced from 6-9.6 to 2.8days, suggesting protection of environmental contamination, considering cats as the primary source of contamination. The intranasally and rectally administered rhoptry vaccines were able to partially protect cats against T. gondii cysts on being challenged; however, the intranasal method of vaccination yielded better results relative to the rectal route.
PMID: 22542988 [PubMed - as supplied by publisher]
Oocyst shedding in cats vaccinated by the nasal and rectal routes with crude rhoptry proteins of Toxoplasma gondii
Zulpo DL, Headley SA, Biazzono L, da Cunha IA, Igarashi M, de Barros LD, Taroda A, Cardim ST, Bogado AL, Navarro IT, Garcia JL.
Protozoology Laboratory, Departamento de Medicina Veterinária Preventiva, Universidade de Londrina-UEL, P.O. Box 6001, 86050-970 Londrina, PR, Brazil.
During this study, cats were immunized by the intranasal and rectal routes with crude rhoptry proteins of Toxoplasma gondii admixed with Quil-A. Twenty-five domestic short hair cats divided into five groups (n=5) were used during this evaluation: G1 and G3 cats received 200μg of the rhoptry proteins with Quil-A (20μg) by the intranasal and rectal routes, respectively; G2 and G4 cats received bovine serum albumin (BSA, 200μg/dose) with Quil-A (20μg); and G5 animals served as unvaccinated controls. All treatments were performed at days 0, 21, 42, and 63. The challenge was done with 800 cysts of the ME49 of T. gondii strain at day 70 (challenge day). The serum IgG, IgM, IgA, and fecal IgA antibody levels were evaluated by using the indirect enzyme-linked immunosorbent assay (ELISA). Some animals produced antibody levels beyond cut-off; however, two animals from G1 (OD(mean)=0.308, OD(cut-off)=0.200) and three from G3 (OD(mean)=0.254) demonstrated IgG levels on being challenged, with similar results occurring in two cats from G1 to IgM (OD(mean)=0.279, OD(cut-off)=0.200). Fecal IgA levels were detected in all G1 cats (OD(mean)=0.330, OD(cut-off)=0.065), and in one cat from G3 (OD(mean)=0.167). The serum and fecal humoral immune responses did not correlate with oocyst shedding. Oocyst shedding varied from 98.4% (G1), 87.5% (G2), 53.0% (G3), to 58% (G4), and was lower than that of G5 cats. The prepatent period of cats vaccinated intranasally (G1) was reduced from 6-9.6 to 2.8days, suggesting protection of environmental contamination, considering cats as the primary source of contamination. The intranasally and rectally administered rhoptry vaccines were able to partially protect cats against T. gondii cysts on being challenged; however, the intranasal method of vaccination yielded better results relative to the rectal route.
PMID: 22542988 [PubMed - as supplied by publisher]
Seroprevalence of anti-Toxoplasma gondii IgG antibody in patients with schizophrenia
Trop Biomed. 2012 Mar;29(1):151-9.
Seroprevalence of anti-Toxoplasma gondii IgG antibody in patients with schizophrenia
Emelia O, Amal RN, Ruzanna ZZ, Shahida H, Azzubair Z, Tan KS, Noor Aadila S, Siti N AM, Aisah MY.
Department of Parasitology and Entomology, Faculty of Medicine, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
Schizophrenia is a pervasive neuropsychiatric disease of unknown cause. Previous studies have reported that toxoplasmosis may be a possible cause of schizophrenia. To ascertain possible relationship between Toxoplasma gondii and schizophrenia, a cross sectional study, employing an enzyme-linked immunosorbent assay (ELISA) was performed to study the seroprevalence of anti-T. gondii IgG antibody in schizophrenic patients. Furthermore, demographic data analysis from schizophrenic patients were analysed to associate toxoplasmosis with schizophrenia. A total of 288 serum samples from schizophrenic patients (n=144) and psychiatrically healthy volunteers (n=144) were recruited in this study. Interestingly, a significant result in the serointensity rate of anti-T. gondii IgG antibody (> 60IU/mL) in schizophrenic patients (61.1%) was demonstrated as compared to psychiatrically healthy volunteers (40.8%) (X² = 4.236, p < 0.050). However, there was no significant difference between the seropositivity rate of anti-T. gondii IgG antibody between the two groups. Analysis from demographic data revealed that the seropositivity rate of anti-T. gondii IgG antibody in schizophrenic patients was significantly associated with age group of more than 40 years old (p=0.007) and between ethnic (p=0.046). Nevertheless, no significant association between seropositivity rate of anti-T. gondii IgG antibody with gender (p=0.897), duration of illness (p=0.344) and family history of schizophrenia (p=0.282) in these patients. Thus, this finding is essential as a preliminary data in Malaysia to establish the association between T. gondii and schizophrenia.
PMID: 22543615 [PubMed - in process]
Seroprevalence of anti-Toxoplasma gondii IgG antibody in patients with schizophrenia
Emelia O, Amal RN, Ruzanna ZZ, Shahida H, Azzubair Z, Tan KS, Noor Aadila S, Siti N AM, Aisah MY.
Department of Parasitology and Entomology, Faculty of Medicine, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
Schizophrenia is a pervasive neuropsychiatric disease of unknown cause. Previous studies have reported that toxoplasmosis may be a possible cause of schizophrenia. To ascertain possible relationship between Toxoplasma gondii and schizophrenia, a cross sectional study, employing an enzyme-linked immunosorbent assay (ELISA) was performed to study the seroprevalence of anti-T. gondii IgG antibody in schizophrenic patients. Furthermore, demographic data analysis from schizophrenic patients were analysed to associate toxoplasmosis with schizophrenia. A total of 288 serum samples from schizophrenic patients (n=144) and psychiatrically healthy volunteers (n=144) were recruited in this study. Interestingly, a significant result in the serointensity rate of anti-T. gondii IgG antibody (> 60IU/mL) in schizophrenic patients (61.1%) was demonstrated as compared to psychiatrically healthy volunteers (40.8%) (X² = 4.236, p < 0.050). However, there was no significant difference between the seropositivity rate of anti-T. gondii IgG antibody between the two groups. Analysis from demographic data revealed that the seropositivity rate of anti-T. gondii IgG antibody in schizophrenic patients was significantly associated with age group of more than 40 years old (p=0.007) and between ethnic (p=0.046). Nevertheless, no significant association between seropositivity rate of anti-T. gondii IgG antibody with gender (p=0.897), duration of illness (p=0.344) and family history of schizophrenia (p=0.282) in these patients. Thus, this finding is essential as a preliminary data in Malaysia to establish the association between T. gondii and schizophrenia.
PMID: 22543615 [PubMed - in process]
Toxoplasma on the brain: understanding host-pathogen interactions in chronic CNS infection
J Parasitol Res. 2012;2012:589295. Epub 2012 Mar 22.
Toxoplasma on the brain: understanding host-pathogen interactions in chronic CNS infection
Kamerkar S, Davis PH.
Department of Biology, University of Nebraska at Omaha, Omaha, NE 68182, USA.
Toxoplasma gondii is a prevalent obligate intracellular parasite which chronically infects more than a third of the world's population. Key to parasite prevalence is its ability to form chronic and nonimmunogenic bradyzoite cysts, which typically form in the brain and muscle cells of infected mammals, including humans. While acute clinical infection typically involves neurological and/or ocular damage, chronic infection has been more recently linked to behavioral changes. Establishment and maintenance of chronic infection involves a balance between the host immunity and parasite evasion of the immune response. Here, we outline the known cellular interplay between Toxoplasma gondii and cells of the central nervous system and review the reported effects of Toxoplasma gondii on behavior and neurological disease. Finally, we review new technologies which will allow us to more fully understand host-pathogen interactions.
PMID: 22545203 [PubMed - in process]
Toxoplasma on the brain: understanding host-pathogen interactions in chronic CNS infection
Kamerkar S, Davis PH.
Department of Biology, University of Nebraska at Omaha, Omaha, NE 68182, USA.
Toxoplasma gondii is a prevalent obligate intracellular parasite which chronically infects more than a third of the world's population. Key to parasite prevalence is its ability to form chronic and nonimmunogenic bradyzoite cysts, which typically form in the brain and muscle cells of infected mammals, including humans. While acute clinical infection typically involves neurological and/or ocular damage, chronic infection has been more recently linked to behavioral changes. Establishment and maintenance of chronic infection involves a balance between the host immunity and parasite evasion of the immune response. Here, we outline the known cellular interplay between Toxoplasma gondii and cells of the central nervous system and review the reported effects of Toxoplasma gondii on behavior and neurological disease. Finally, we review new technologies which will allow us to more fully understand host-pathogen interactions.
PMID: 22545203 [PubMed - in process]
Subscribe to:
Posts (Atom)